TWI577217B - A method of forming n-hop synchronous network for d2d communication and devices using the same - Google Patents

Description

Method of forming an N-hop synchronization network for inter-device communication and apparatus using the same

The present disclosure is directed to a method of forming an N-hop synchronization network for device-to-device (D2D) communication and apparatus using the same.

D2D communication is a technology that allows user equipment (UE) to communicate directly with neighboring UEs via a licensed or unlicensed frequency band under the control of a wireless communication system, and such technology will enable the wireless communication network to increase The system spectral efficiency reduces the transmit power of each terminal and reduces the resource consumption of the wireless communication network. For commercial and public safety purposes, one of the design considerations for D2D communication may be that the UE is within the coverage of the cellular network, partially within the coverage of the cellular network, and in both The coverage of the cellular network is not even within the coverage of the cellular network at all, making D2D communication available to the UE. Moreover, it may be necessary to consider the potentially large number of UEs participating simultaneously. In order to meet the aforementioned design considerations, N jump points can be utilized. Step network.

Figure 1A illustrates the network coverage of a network that does not use an N-hop synchronization network. Because the base station 101 or cluster head has a limited coverage 102, the base station 101 or cluster head may not be able to reach the UE 103 outside its coverage area 102. FIG. 1B illustrates the concept of an N-hop synchronization network. One of the ideas behind the N-hop synchronization network is that it may be difficult to have one SYN source cover all UEs outside the coverage of the network, so some UEs 111 can assume forwarding or even provide time alignment and frequency synchronization information independently. To cover tasks of UEs outside of coverage 102.

UE-to-network timing alignment and/or synchronization will need to be implemented before D2D communication can begin between two or more UEs. The UE will be able to synchronize directly or indirectly to the network by synchronizing to a D2D Synchronization Signal (D2DSS) that can be used to obtain timing and synchronization information. FIG. 1C illustrates a resource pool for D2D communication. After receiving the D2DSS, UEs that are within the coverage of the network or outside the coverage of the network will perceive a resource pool that may contain resources for transmitting D2D data resources in a specific time slot and/or spectrum.

FIG. 1D illustrates a hypothetical N-hop synchronization network. Such a hypothetical N-hop synchronization network may include, but is not limited to, a cluster header 141, at least one D2D synchronization source (SYN source) 142, and at least one D2D capable normal UE 143. The cluster header 141 may be a base station (e.g., an eNB) or a UE.

The UE 143 can synchronize to the network by receiving a D2D synchronization signal (D2DSS) that the UE may be able to implement timing alignment and frequency synchronization. Such D2DSS It may be provided by a cluster header 141 that may be a base station (e.g., an eNB) or a UE. If the cluster header 141 is a base station, then the D2DSS will be the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) transmitted by the base station. In the event that the UE is unable to receive timing alignment and frequency synchronization information from the network, the UE may act as an independent cluster header 141. The D2DSS may be transmitted or relayed by a SYN source 142 that may be another D2D capable UE for the purpose of providing network coverage outside of the network coverage or near the boundaries of the network coverage.

The SYN source 142 scans the first D2DSS from the cluster or from other SYN sources 142 for reference. If the first D2DSS has been detected and subsequently selected as a reference, the SYN source can be synchronized to the first D2DSS before the SYN source 142 can transmit the second D2DSS derived based on the first D2DSS. If D2DSS is not detected at all, then despite this, the UE may still transmit the second D2DSS without a timing reference from the first D2DSS. If any SYN source 142 has detected a change in D2DSS, then the SYN source 142 may reselect the D2DSS as a reference.

In order to synchronize a large number of UEs located inside or outside the network, one method may be to allow all UEs to be SYN sources. However, such methods may have unsatisfactory consequences such as unnecessary energy consumption and D2DSS interference. Assuming that there is no timing alignment information available for D2DSS forwarding timing, timing differences caused by propagation delay between SYN sources may cause D2DSS interference. Therefore, it will be necessary to reduce the number of SYN sources.

In order to reduce the number of UEs that are SYN sources while maintaining a large synchronization area, a mechanism involving the use of "Cluster Head Muting" to reduce the number of cluster heads may be used to involve the use of "predefined reference signal received power ( The Reference Signal Receiving Power (RSRP) threshold mechanism reduces the number of SYN sources.

For the "Predefined Reference Signal Received Power (RSRP) Threshold value", if the UE cannot detect other cluster heads or SYN sources, the UE will become a cluster header with a skip point count = 0. The jump point count is the number of jump points from the cluster head to the SYN source. The UE will only become the SYN source if the maximum received power from the neighboring SYN source does not exceed a predefined threshold (eg, -80 dBm / -103 dB path gain). In general, the UE will become the SYN source with the hop count N when the UE detects or synchronizes to a SYN source with a lower hop count (N-1). For "cluster head disable", when the SYN source detects two or more cluster headers, the SYN source will select one of them as the synchronization source. This means that the remaining cluster heads that are not selected by the SYN source can disable their operation when receiving a D2DSS from a SYN source having a skip count of, for example, n=1.

2A through 2D illustrate different hypothetical scenarios involving an N-hop synchronization network operating in accordance with the aforementioned first mechanism and second mechanism. The hypothetical N-hop synchronization network of FIG. 2A will include a cluster head 201 having a first power range 202 and a second power range 203. The UE (e.g., 204) within the first power range 202 will be synchronized to the cluster head 201 and the maximum received power from the cluster head 201 exceeds a predefined threshold. UE between the first power range 202 and the second power range 203 (eg, 205) It will also be synchronized to the cluster head 201, and the maximum received power from the cluster head 201 does not exceed a predefined threshold. Therefore, these UEs (eg, 205) will act as SYN sources. For UEs (e.g., 206) that cannot detect other cluster heads or SYN sources, these UEs (e.g., 206) may become cluster heads with a skip point count = 0.

Similarly, for the hypothetical N-hop network of Figure 2B, the UE 211, which will act as a SYN resource, because the maximum detected power from the cluster head 210 is below a predefined threshold. In the hypothetical N-hop synchronization network of FIG. 2C, when the UE 212 acting as the SYN source detects the two cluster heads 213, 214, the "cluster head disable" context can be utilized. In this scenario, the UE 212 will select one of the two cluster heads 213, 214 as the source to which it is synchronized. Assuming cluster head 213 is selected, cluster head 214 that has not been selected by UE 212 may disable its operation upon receiving D2DSS from UE 212 having a hop count of, for example, n=1.

However, this mechanism involving "predefined reference signal received power (RSRP) threshold" and "cluster head disable" will encounter difficulties as illustrated in the hypothetical N-hop synchronization network of Figure 2D. In such extreme cases, this mechanism may be due to a skewed arrangement of the cluster head and the SYN source causing a substantial time difference. If the SYN source forwards subsequent D2DSS based on previously received D2DSS (ie, no timing advance is applied for D2DSS forwarding timing), then subsequent D2DSS timing may be delayed when propagating.

For Figure 2D, assuming that the cluster head 220 initiates a D2DSS with a propagation delay T1_0 that may be zero, the SYN source 221 will receive the D2DSS with a propagation delay T1_1, which will receive the forwarded D2DSS with a propagation delay T1_2, And the SYN source 223 will receive the forwarded D2DSS with a propagation delay T1_3. This would mean that if UE1 241 is participating in D2D communication with UE2 242 (as in step S250), then the message will typically be out of sync, and thus a Cyclic Prefix (CP) is required to cover the D2D transmitter such as UE2 242. The time difference from the D2D receiver of UE1 241. In a general N-hop synchronous network, the length of the CP should be greater than TA+N×(TA/2), where N is the maximum hop count of the N-hop synchronization network, and TA is the largest within the coverage of the D2DSS. Propagation delay. This means that the length of the CP used in the scenario of Figure 2D will substantially exceed the current CP of the Long Term Evolution (LTE) and LTE-Advanced (LTE-A) communication systems. Therefore, different solutions can be proposed to at least avoid the aforementioned problems.

Accordingly, the present disclosure is directed to a method of forming an N-hop synchronization network for D2D communication and an apparatus using the same.

In one of the exemplary embodiments, the present disclosure is directed to a method of forming an N-hop synchronization network for inter-device (D2D) communication, suitable for a User Equipment (UE), which method will include Not limited to: detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; selecting a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is Neighboring synchronization source transmission with hop count = i, wherein the hop count counts the number of hops from the eNB to the neighboring synchronization source, and i is detected from the one or more neighboring synchronization sources Minimum jump point count; and if there is more than one adjacent point with jump point count = i Step source, then selecting the first SS to have a maximum reference signal received power (RSRP) detected by the UE; and if the RSRP of the first SS does not exceed a predefined threshold, then: Operating with a synchronization source; and transmitting the SS based on the first SS.

In one of the exemplary embodiments, the present disclosure is directed to a method of forming an N-hop synchronization network for inter-device (D2D) communication, suitable for a User Equipment (UE), including but not limited to: Detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; selecting a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is counted by having a jump point a neighboring synchronization source transmission of =i or i+1, wherein the hop count counts the number of hops from the eNB to the neighboring synchronization source, and i is detected from the one or more neighboring synchronization sources a minimum hop count to arrive; and if there is more than one neighboring synchronization source of the hop count = i or i+1, then the first SS is selected to have a maximum reference signal received by the UE Power (RSRP); and if the RSRP of the first SS does not exceed a predefined threshold, then: operate as a synchronization source; and transmit the SS based on the first SS.

In one of the exemplary embodiments, the present disclosure is directed to a method of forming an N-hop synchronization network for inter-device (D2D) communication, suitable for a User Equipment (UE), the method including but not Limited to: detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; selecting a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is caused by having a jump Neighboring synchronization source transmission with point count = i, wherein the hop count is counted from the eNB to the neighboring synchronization source Number of jump points, and i is the minimum jump point count detected from the one or more neighboring synchronization sources; and if there is more than one adjacent sync source with skip point count = i, then the first SS is selected to have a maximum reference signal received power (RSRP) detected by the UE; and if the RSRP of the first SS does not exceed a predefined threshold or if the hop point of the neighboring synchronization source The difference in count is greater than two, then: operating as a synchronization source; and transmitting the SS based on the first SS.

In one of the exemplary embodiments, the present disclosure is directed to a method of forming an N-hop synchronization network for inter-device (D2D) communication, suitable for a User Equipment (UE), the method including but not Limited to: detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; selecting a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is caused by having a jump Neighboring synchronization source transmission with point count = i, wherein the hop count counts is the number of hops from the eNB to the neighboring synchronization source, and i is detected from the one or more neighboring synchronization sources a minimum hop count count; and if the UE can extend coverage based on location information of neighboring synchronization sources or if the difference of the hop counts of the neighboring synchronization sources is greater than two, then: operate as a synchronization source; The SS is transmitted based on the first SS.

The above described features and advantages of the invention will be apparent from the following description.

However, it is to be understood that the summary is not intended to be in any way or limitation. Moreover, the present disclosure will include modifications and modifications obvious to those skilled in the art.

101‧‧‧ base station

102, 312‧‧‧ Coverage

103, 111, 143, 204, 205, 206, 211, 212, 512, 513, 652‧‧‧ user equipment

141, 201, 210, 213, 214, 220, 320‧‧ ‧ cluster head

142‧‧‧Synchronization source

202‧‧‧First power range

203‧‧‧second power range

221, 222, 223, 651‧‧‧ synchronization sources

241‧‧‧User equipment 1

242‧‧‧User equipment 2

301, 321, 851, 903‧‧‧ first user equipment

302, 322, 904‧‧‧ second user equipment

303, 323‧‧‧ third user equipment

311‧‧‧eNB

325‧‧‧First coverage

326‧‧‧second coverage

327, 701, 702, 703, 704‧‧‧ first range

328, ‧‧‧second range

451‧‧‧State A

452‧‧‧State B

453‧‧‧State C

454‧‧‧Unsynchronized state

501‧‧‧First cluster

502‧‧‧Second cluster

511‧‧‧eNB

601‧‧‧Inter-device synchronization signal

602‧‧‧Inter-device resource pool

603‧‧‧ Periodic

801, 802, 803, 804‧‧‧ shadow areas

853‧‧‧Synchronization source

901‧‧‧First synchronization source

902‧‧‧Second synchronization source

1011‧‧‧Adjacent synchronization source

1012‧‧‧ Coverage circle

1101‧‧‧Processing circuit

1102‧‧‧ analog/digital digit/analog converter

1103‧‧‧transmitter

1104‧‧‧ Receiver

1105‧‧‧Antenna

S250, S401~S408, S1201~S1207, S1301~S1307, S1401~S1407, S1501~S1505‧‧‧ steps

The drawings are included to provide a further understanding of the present disclosure, and the drawings are incorporated in this specification and constitute a part of this specification. The drawings illustrate the embodiments of the disclosure, and together with the description

Figure 1A illustrates the network coverage of a network that does not use an N-hop synchronization network.

FIG. 1B illustrates the concept of an N-hop synchronization network.

FIG. 1C illustrates a resource pool for D2D communication.

FIG. 1D illustrates a hypothetical N-hop synchronization network operating in an LTE/LTE-A communication system.

2A illustrates a first hypothetical N-hop synchronization network operating in an LTE/LTE-A communication system.

2B illustrates a second hypothetical N-hopping point synchronization network operating in an LTE/LTE-A communication system.

2C illustrates a third hypothetical N-hopping point synchronization network operating in an LTE/LTE-A communication system.

2D illustrates a fourth hypothetical N-hopping point synchronization network operating in an LTE/LTE-A communication system.

FIG. 3A illustrates an example of an N-hop synchronization network based on the first exemplary embodiment of the present disclosure.

FIG. 3B illustrates the concept of forming an N-hop synchronization network in accordance with the first exemplary embodiment of the present disclosure.

FIG. 3C illustrates the overall coverage of the N-hopping point synchronization network of FIG. 3A.

FIG. 4 illustrates a state transition diagram in accordance with one of the exemplary embodiments of the present disclosure.

FIG. 5 illustrates a situation in which a UE determining a SYN source decision procedure according to one of the exemplary embodiments of the present disclosure.

6 illustrates a timing diagram of a SYN source operating in state A in accordance with one of the exemplary embodiments of the present disclosure.

FIG. 7A illustrates the concept of forming an N-hop synchronization network in accordance with a second exemplary embodiment of the present disclosure.

Figure 7B illustrates the overall coverage of the N-hop synchronization network of Figure 7A.

FIG. 8A illustrates the concept of forming an N-hop synchronization network in accordance with a third exemplary embodiment of the present disclosure.

Figure 8B illustrates the overall coverage of the N-hopping point synchronization network of Figure 8A.

FIG. 9 illustrates a concept of forming an N-hop synchronization network in accordance with a fourth exemplary embodiment of the present disclosure.

FIG. 10A illustrates that one of the exemplary embodiments of the present disclosure determines whether a UE can extend coverage by sampling.

FIG. 10B illustrates determining whether the UE can extend the coverage by using a Voronoi diagram.

Figures 10C and 10D illustrate the use of the Voronoi diagram of Figure 10B.

11 illustrates an exemplary D2D capable user device in accordance with one of the exemplary embodiments of the present disclosure.

Figure 12 is a flow chart relating to a first exemplary embodiment of the present disclosure.

Figure 13 is a flow chart relating to a second exemplary embodiment of the present disclosure.

Figure 14 is a flow chart relating to a third exemplary embodiment of the present disclosure.

Figure 15 is a flow chart relating to a fourth exemplary embodiment of the present disclosure.

Reference will now be made in detail to the present exemplary embodiments embodiments Whenever possible, the same reference numerals are used in the drawings and the description

In the present disclosure, the aforementioned D2D synchronization concerns are addressed by proposing a method of forming an N-hop synchronization network for D2D communication. In the proposed method, some UEs outside the coverage of the network may become D2DSYN sources to form an N-hop synchronization network because these SYN sources will periodically broadcast D2D synchronization signals (D2DSS). By utilizing D2DSS, a D2D capable UE will be able to synchronize with neighboring UEs and then perform D2D communication with these UEs.

The present disclosure proposes a first exemplary embodiment as illustrated in Figures 3A through 3C and described in the corresponding written description of the figures. FIG. 3A illustrates an example of an N-hop synchronization network of the first exemplary embodiment. For the example of FIG. 3A, it is assumed that the N-hop synchronization network includes, but is not limited to, the eNB 311 and a plurality of UEs served by the network, including but not limited to the first UE 301, the second UE 302, and the third UE 303. It is assumed that the first UE 301 is within the coverage 312 of the eNB 311 and that the second UE 302 and the third UE 303 are outside the coverage of the eNB 311. It is assumed that the UEs 301 to 303 have D2D capabilities.

The eNB 311 may provide frequency synchronization and timing information for normal UEs below the coverage area 312 by periodically transmitting a primary synchronization signal (PSS) and a second synchronization signal (SSS) that the normal UE will be able to synchronize to the eNB 311. A normal UE will not be a SYN source and will be a UE with or without D2D capability. However, if the power of the eNB 311 received by the UE (eg, UE 301) within coverage 312 does not exceed a predefined threshold, such a UE may become a SYN source. The power received by the UE can be measured based on maximum or average reference signal received power (RSRP). The predefined threshold value can be any value between, for example, -80 dBm to -103 dBm, although the disclosure is not limited to these numbers herein.

Next, define the jump point count. The jump point count of the SYN source is defined as the number of jump points from the cluster head to the SYN source. Since the eNB 311 will be both the cluster head and the SYN source, the hop point count of the eNB 311 is zero. Assuming that the UE 301 acts as a SYN source (because the maximum RSRP of the eNB 311 does not exceed a predefined threshold), the number of hops from the eNB to the UE 301 is 1, and thus the UE 301 has a hop count of one. Based on the same basic principle, the UE 302 will have a hop count of 2 and the UE 303 will have a hop count of 3.

For UEs outside of coverage 312 (e.g., UEs 302 and 303), it will be determined if these UEs will act as SYN sources. In general, for UEs outside of coverage 312, if the received power from the neighboring SYN source does not exceed a predefined threshold, then the UE becomes the SYN source. One condition is that the adjacent SYN source described above has a minimum hop count count detected by the UE. If the UE detects that there are multiple neighboring SYN sources with the smallest hop count, then the aforementioned neighbor SYN source will have The SYN source of the highest received power detected by the UE. The highest received power can be the maximum or average RSRP. For the example of FIG. 3A, the UE 302 will be able to obtain a timing reference from the overlay UE 301, which will be able to obtain a timing reference from outside the overlay UE 302. In this way, not only will the coverage of the network for D2D communication be extended, but devices outside of coverage 312 will be synchronized to the network.

FIG. 3B illustrates the disclosure of the first exemplary embodiment with another example consistent with FIG. 3A. The example of Figure 3B shows a network comprising a cluster header 320 with a hop count of 0 and a plurality of UEs (represented by diamonds). The cluster header 320 may be an eNB or a UE and is assumed to have a first coverage 325 and a second coverage 326. In general, if the maximum RSRP from a neighboring SYN source with a hop count = i does not exceed a predefined threshold and i is the smallest hop count detected by the UE, then the UE becomes the SYN source. The first range 325 is defined as the signal strength outside the first range 325 will be less than the predefined threshold value, and the signal strength outside the second range 326 will be weak such that the UE outside the second range 326 will It cannot be received from the cluster header 320.

The first UE 321 is within the second range 326 and is therefore considered to be within the coverage of the cluster head 320, and the UE 321 outside the first range 325 is also satisfied to have the smallest hop count count (ie, the cluster head 320) The maximum RSRP of the neighboring SYN source with a skip count of zero is less than the criterion for the predefined threshold value; therefore, the UE 321 will act as the SYN source with the hop count of one. The second UE 322 is outside of the second range 326 of the cluster head 320 and will not be able to perceive the message from the cluster head 320. But the second UE 322 is within the coverage or second range 328 of the first UE 321 and And outside of the first range 327 of the first UE 321 which is the SYN source for the second UE 322 with the smallest hop count. Therefore, the second UE 322 will synchronize to the first UE 321 with the hop count 2 . By applying a similar basic principle, the third UE 323 will act as a third SYN source with a hop count of three.

Alternatively, if the UE detects that the maximum RSRP from the neighboring SYN source with the smallest hop count (ie, the hop count of the cluster header 320 is zero) is greater than the predefined threshold, then the UE may become the normal UE instead of the SYN source. Moreover, if the UE is unable to perceive any message from any SYN source, the UE may act as an independent cluster header and provide its own frequency synchronization information for D2D communication with neighboring UEs.

It is noted that for the first exemplary embodiment, the UE located in the shaded area of FIG. 3B may not be the SYN source. Since the structure of the N-hop synchronization network will be reformed to a structure similar to the number of UEs in FIG. 3C, the extreme case of the case of FIG. 3B, for example, similar to the case of FIG. 2D, will be significantly improved.

Next, the present disclosure provides operational details of the UE in accordance with the state diagram as illustrated in FIG. The UE may have at least four states. In state A 451, the UE will be a normal UE and not a SYN source. In this state, the UE will synchronize to the D2DSS received from the SYN source. The D2DSS can include primary D2DSS (PD2DSS) and secondary D2DSS (SD2DSS). The SYN source may be a UE or may be a base station (e.g., an eNB). If the SYN source is an eNB, the D2DSS may contain PSS and SSS. In state B 452, the UE will act as a SYN source in response to receiving a timing reference from another external source from the network. In state C 453, the UE will be without any external In the case of an auxiliary of the timing reference, it acts as a separate SYN source. In the unsynchronized (UNSYN) state 454, the UE may be in the initial state just after powering up or just exiting the sleep mode. The UE may also be in a temporary state other than state A 451, state B 452, and state C 453 (ie, the UE is not a SYN source, nor is it a UE that is synchronized to the SYN source).

When the UE is operating as a normal UE in state A 451, the UE will execute a program called SYN source decision program A (ie, S402) to determine if it is likely to operate in state B 452 as a SYN source. In SYN source decision program A, assuming that the minimum hop count for neighboring SYN sources is less than N, where N is a non-zero integer, the UE may operate in state B 452 in the situation described below. If the maximum received power from a neighboring SYN source with a hop count = i does not exceed a predefined threshold, where i is the minimum hop count detected by the UE during a certain time period, then the UE will operate in state B 452. This will indicate that the SYN source decision program was successful. Furthermore, it is assumed that the UE 513 is in the situation of FIG. 5, and between the first cluster 501 and the second cluster 502, wherein the first cluster 501 is prioritized over the second cluster 502 because the first cluster 501 operates through the eNB 511. high. In the SYN source decision program A, if the UE 513 is synchronized to the eNB 511 as a normal UE, it operates in state A 451 and for the cyclic redundancy code (cyclic redundancy code) of the data packets received in the D2D resource pool. The CRC) checks that the error rate is greater than the threshold, then the UE 513 may blindly scan the D2DSS from another cluster (ie, another N-hop synchronization network) in a short period of time. If a D2DSS from another cluster with a lower priority order has been found (e.g., D2DSS from UE 512), then UE 513 will operate in state B 452 and remain synchronized to the eNB. 511. However, if the UE 513 operating as a normal UE in state A 451 synchronizes to the UE 512 and finds a D2DSS from another cluster with a higher priority order (e.g., PSS/SSS from the eNB 511), the UE 513 will synchronize. Go to PSS/SSS with higher priority and operate in state B 452.

In the present disclosure, the prioritization of all synchronization signals is described as follows. The following prioritization rules will apply to all exemplary embodiments in the same manner. Among all the different synchronization signals, the PSS/SSS from the eNB has the highest priority. The D2DSS derived from the PSS/SSS will be considered to have a higher priority than the D2DSS derived from any other D2DSS. The priority order of D2DSS transmitted by a SYN source having a smaller hop count is higher than that of a D2DSS transmitted by a SYN source having a larger hop count.

In addition to executing the SYN source decision program A, the UE operating in state A 451 will blindly scan the PSS/SSS from the eNB. If PSS/SSS is found, then in step S401 the UE will still operate in state A 451 and synchronize to PSS/SSS. The UE will also periodically scan for D2DSS from neighboring synchronization sources belonging to the same cluster. If a D2DSS with a higher priority is found, then in step S401, the UE will still operate in state A 451 and synchronize to the D2DSS. In order to perform the prioritization of the synchronization signal and the SYN source decision program A, the UE may also receive the skip point count information from its neighboring SYN source. In addition, the UE will keep monitoring the D2DSS it is synchronized to periodically. For example, referring to FIG. 6, UE 652 in state A synchronizes to D2DSS 601 from SYN source 651 and monitors D2D resource pool 602 for D2D discovery and communication. May monitor with periodicity 603 D2DSS 601. If the D2DSS 601 is missing or cannot be detected or missed multiple times, then in step S405, the UE 652 will operate in the UNSYN state 454.

In general, the operation of the SYN source in state B 452 will be described. The SYN source in state B 452 will execute a program called SYN source decision program B (i.e., S404) to determine if it should operate in state A 451 as a normal UE. In the SYN source decision program B, if the maximum received power from the adjacent SYN source with the hop count = i exceeds a predefined threshold (where i is the minimum hop count detected by the SYN source within a certain time period) Then, in step S404, the SYN source will operate as a normal UE in state A 451. This will indicate that the SYN source decision program failed.

In addition to executing the SYN source decision program B, the SYN source in state B 452 will periodically and blindly scan the PSS/SSS from the eNB and the D2DSS from neighboring synchronization sources belonging to other clusters. In addition, the SYN source will also periodically scan D2DSS from neighboring synchronization sources belonging to the same cluster. If PSS/SSS is found, then in step S403, the SYN source will still operate in state B 452 and broadcast D2DSS based on the PSS/SSS. Otherwise, if a D2DSS with a higher priority is found, then in step S403, the SYN source will still operate in state B 452 and broadcast D2DSS based on the higher priority order D2DSS. In order to perform the prioritization of the synchronization signals and the SYN source decision program B, the SYN source can also receive the skip point count information from its neighboring SYN source. Likewise, if the SYN source detects another SYN source with a lower hop count (n-1) and then periodically broadcasts the hop count information, the SYN source configures its hop count to n. In addition, like exercise For the UE in state A 451, the SYN source in state B 452 will also periodically maintain monitoring of the D2D resource pool and its synchronized D2DSS. If the D2DSS to which it is synchronized is lost or missed multiple times, then in step S405, the SYN source will operate in the UNSYN state 454.

The operation of the cluster header in state C (e.g., 512 of Figure 5 instead of 513) is described as follows. The cluster head in state C will periodically and blindly scan the SS containing PSS/SSS and D2DSS from other clusters. For the situation similar to FIG. 5 (where the priority of the first cluster 501 is higher than the second cluster 502), if a higher priority D2DSS is found, the cluster head 512 will synchronize to the higher priority D2DSS, updating the hop point Counting, and operating in state B 452 in step S408. The cluster head 512 may monitor the D2D resource pool (eg, 602) for D2D discovery and communication. The cluster head 512 can also periodically broadcast its hop count information and transmit its own D2DSS. In this case, cluster 512 previously supplied its own SS without a timing reference; but after detecting a higher priority D2DSS, cluster head 512 will be able to synchronize to the known SS as a timing reference and based on The timing reference provided by the known SS transmits its own D2DSS.

FIG. 7A illustrates the concept of forming an N-hop synchronization network in accordance with a second exemplary embodiment of the present disclosure. The situation of Figure 7A is similar to the situation of Figures 3A and 3B, and thus a repetitive description of the situation is avoided. However, the criteria for forming a SYN source are different. For the second exemplary embodiment, the criterion for making the UE a SYN source is if or only if the maximum RSRP from the neighboring SYN source with the hop count = i or i+1 does not exceed the predefined threshold The UE will become the SYN source, where i is the UE. The smallest jump point count detected. If the maximum RSRP from the neighboring SYN source with the hop counts = i and i+1 does exceed the predefined threshold, then the UE does not become the SYN source, operates as a normal UE, and with one of the adjacent SYN sources Synchronize.

In FIG. 7A, by following the aforementioned criteria, it can be derived that if the UE is within the shaded portions of the four first ranges 701, 702, 703, and 704 corresponding to the four different cluster heads, the UE is for the second according to the foregoing criteria. The embodiment will not be a SYN source. Therefore, even for the extreme case of FIG. 2D, it is still possible to reform the N-hop synchronization network. If the number of UEs is high, the N-hop synchronization network may be formed similar to the structure shown in FIG. 7B.

To describe the second embodiment in further detail, reference will be made to the state diagram of FIG. For the second embodiment, the SYN source decision program A will assume that the minimum hop count for neighboring SYN sources is less than N, where N is a non-zero integer. The maximum received power at or only from an adjacent SYN source with a hop count = i or i + 1 does not exceed a predefined threshold (where i = the neighbor SYN source detected by the UE during a certain time period) In the case of the minimum jump point count), the UE will operate in state B 452.

When the UE is in a situation similar to that of FIG. 5 (where there is a first cluster 501 whose priority order is higher than the second cluster 502), if the error rate of the CRC check on the data packet received in the D2D resource pool (eg, 602) Above the threshold, the UE will blindly scan the SS containing D2DSS and PSS/SSS from another cluster in a short period of time. If it has been determined that the D2DSS from another cluster is in a lower priority order, then since program A has succeeded, the UE will operate in state B 452 and will continue to synchronize to the D2DSS of the current cluster. However, if it has been determined from another cluster The priority of the SS is higher than the SS of the current cluster, then the UE will synchronize to the D2DSS with a higher priority, and thus this program is also considered successful and operates in state B 452.

For the second exemplary embodiment, the SYN source decision program B is if the maximum RSRP received by the UE from the neighboring SYN source with the hop counts = i and i +1 exceeds a predefined threshold (where i is as the SYN source) The neighboring SYN source with the smallest hop count detected during a certain time period), then in step S402, the UE will operate in state A because the program has failed.

For the operation of the UE in the states UNSYN, State A, State B, and State C, the operation of the UE in these states will be the same as the first exemplary embodiment, and thus the description will be avoided.

FIG. 8A illustrates the concept of forming an N-hop synchronization network in accordance with a third exemplary embodiment of the present disclosure. The situation of Figure 8A is similar to the situation of Figures 3A and 3B, and thus a repetitive description of the situation is avoided. However, the criteria for forming a SYN source are different. For the second exemplary embodiment, the criterion for making the UE a SYN source is if the UE receives a maximum RSRP that does not exceed a predefined threshold from the neighboring SYN source and if the hop count difference between adjacent SYN sources is greater than two, Then the UE will become the SYN source. Otherwise, if the UE receives a maximum RSRP that does exceed a predefined threshold value from an adjacent SYN source or if the hop count difference between adjacent SYN sources is not greater than two, the UE may become a normal UE instead of acting as a SYN source. In this case, the UE may be synchronized with one of the neighboring SYN sources.

Based on the aforementioned criteria, it will be apparent if the UE is in the shadow of Figure 8A Within regions 801, 802, 803, and 804, then the UE will not be the SYN source. Even if the extreme case of Figure 2D occurs, it is possible to reform the N-hop synchronization network. The reformed network is shown in Figure 8B. Since the first UE 851 will receive the D2DSS from the SYN source 852 with the hop count = 0 and receive the D2DSS from the SYN source 853 with the hop count 3, the UE 851 may then become the SYN with the hop count 1 according to the aforementioned criteria. source. Moreover, when the first UE 851 becomes a SYN source with a hop count of 1, the SYN source 853 with hop count 3 can update the hop count to 2, and thus it is possible to derive the reformed structure of FIG. 8B from such principles. .

The third exemplary embodiment will be described in more detail when the SYN source decision formula A is described below with reference to the state diagram of FIG. 4, assuming that the minimum hop count of adjacent SYN sources is less than N, where N is a non-zero integer. If the maximum RSRP received by the UE from the neighboring SYN source does not exceed the predefined threshold for a certain period of time, then the UE will operate in state B because the SYN source decision will be considered successful. Moreover, if the hop count difference of the neighboring SYN source is greater than 2 within a certain time period, then the UE will operate in state B 452 because the SYN source decision is also successful.

When the UE is in a situation similar to that of FIG. 5 (where there is a first cluster 501 whose priority order is higher than the second cluster 502), if the error rate of the CRC check on the data packet received in the D2D resource pool (eg, 602) Above the threshold, the UE will blindly scan the SS containing the D2DSS and the PSS/SSS from the other cluster in a short period of time. If it has been determined that the D2DSS from another cluster is in a lower priority order, then since program A has succeeded, the UE will operate in state B 452 and will Continuously sync to the current cluster's D2DSS. However, if it has been determined that the SS from another cluster has a higher priority than the SS of the current cluster, then the UE will synchronize to the D2DSS with a higher priority, and thus this program is also considered successful and operates in state B 452.

For the third exemplary embodiment, the SYN source decision program B is described as follows. If the UE receives a maximum RSRP exceeding a predefined threshold from a neighboring SYN source within a certain period of time, or if the UE is based on the superior node information of the adjacent SYN source instead of the superior node of any adjacent SYN source (where the upper node Is the neighboring SYN source with the smallest hop count value), then the UE will operate in state A 451 and operate as a normal UE instead of a SYN source.

For the third exemplary embodiment, the operation of the UE in the UNSYN state 454, the state A 451, and the state B 452 will be the same as the first exemplary embodiment, and thus the description will be avoided.

For operation of state B 452, the UE will periodically and blindly scan SSs containing D2DSS and PSS/SSS from other clusters. If the SYN source detects a higher priority D2DSS, then the SYN source will synchronize to the D2DSS in step S403, update its hop count and the superior node and remain operational in state B. The SYN source will periodically monitor the D2D resource pool (eg, 602) for D2D discovery and communication and will also monitor the D2DSS. The SYN source will update the hop count and the superior node when the initial superior node disappears. If the D2DSS has been lost or missed multiple times in succession, then in step S405, the UE will operate in the UNSYN state 454.

Moreover, when in state B, the SYN source may receive its neighboring SYN The source's jump point counts information related to the superior node. The SYN source may periodically broadcast its hop count and superior node information, and the SYN source will also broadcast its own D2DSS based on the timing reference from the previously received D2DSS. The SYN resource may then execute the SYN source decision of Program B.

For the third exemplary embodiment, the operation of the cluster head (e.g., 512) in state C 453 is described as follows. When operating as a standalone SYN source, the cluster header (e.g., 512) will periodically and blindly scan the SS containing D2DSS and PSS/SSS from other clusters. If a higher priority SS has been detected, the cluster header (e.g., 512) will be synchronized to the D2DSS, update its hop count and superior node, and operate in state B 452 in step S407. The cluster header (e.g., 512) in state C will also monitor the D2D resource pool (e.g., 602) for D2D discovery and communication, periodically broadcast its hop count information, and without timing reference from another SYN source. In this case (unless a higher priority SS has been detected) periodically broadcasts its own D2DSS.

A concept of forming an N-hop synchronization network in accordance with a fourth exemplary embodiment of the present disclosure is disclosed herein. In general, the criterion for determining whether a UE becomes a SYN source is that if the UE will be able to extend coverage based on location information location information of neighboring SYN sources and if the hop count difference of neighboring SYN sources is greater than 2, then the UE will become a SYN. source. It is assumed that the location information of the UE is available with the aid of a positioning device such as a global positioning satellite (GPS) system. As the name implies, the UE's scalable coverage may mean that if the coverage area of the adjacent SYN source cannot fully cover the coverage area of the UE, the UE may be able to extend the coverage. Wai. If the UE will not be able to extend coverage based on location information of neighboring SYN sources or if the hop point count difference of neighboring SYN sources is not greater than 2, then the UE will operate as a normal UE instead of a SYN source.

In the N-hop synchronization network formed by the fourth exemplary embodiment, the length of the CP may be 2TA. Referring to FIG. 9, when operating in accordance with the fourth exemplary embodiment, the situation of FIG. 9 will not occur even if there is no intersection at the coverage of the coverage of the first SYN source 901 and the second SYN source 902. It is assumed that the first UE 903 is synchronized to the first SYN source 901 and that the second UE 904 is synchronized to the second SYN source 904. The jump point count difference between the first SYN source 901 and the second SYN source 902 will be greater than two. This situation can be demonstrated as follows.

Under the first premise, assuming that the foregoing occurs, the SYN source surrounding the second UE 904 will necessarily have a hop count of greater than or equal to three. Under the second premise, since the first UE 903 does not become the SYN source, this indicates that its neighboring SYN source that already covers the range that may be covered by the first UE 903 contains the location of the second UE 904. Under the third assumption, since the first UE 903 does not become the SYN source, this means that its neighboring SYN sources have all the hop counts equal to or less than two. A fourth premise can be inferred based on the first and third premises: all SYN sources having a range covering the second UE 904 will all have a hop count of equal to or less than two. The fifth premise can be inferred based on the fact that the first premise contradicts the fourth premise Therefore, it can be inferred that since the difference in the jump point count between the first SYN source 901 and the second SYN source 902 will be greater than 2, the situation of FIG. 9 does not occur.

For determining whether the SYN source can extend the coverage based on the location information, A first method based on sampling as illustrated in Figure 10A and (alternatively) a second method based on the use of Voronoi diagram as illustrated in Figures 10B to 10D. Referring to FIG. 10B, if the number of adjacent SYN sources 1011 is greater than one, the Voronoi diagram is drawn based on the adjacent SYN source 1011. First, draw a predefined coverage circle 1012. Next, it should be checked whether the coverage area of the adjacent SYN source 1011 covers the Voronoi vertex inside the circle and also checks whether the coverage area of the adjacent SYN source 1011 covers the Voronoi diagram and the circle The intersection point. If so, the UE cannot extend the coverage. Otherwise, the UE can extend the coverage. If the number of adjacent SYN sources 1011 is not greater than 1, the UE may also extend the coverage. Figures 10C and 10D illustrate the use of the Voronoi diagram of Figure 10B. It should be noted that for FIG. 10D, the new coverage area must cover the Voronoi vertex or cover the intersection between the Voronoi diagram and the predefined circle 1012.

The fourth exemplary embodiment will be described in further detail when the SYN source decision program A is described herein, assuming that the minimum hop count for neighboring SYN sources is less than N, where N is a non-zero integer. Generally, if the UE can cover the coverage, that is, the coverage area of the neighboring SYN source cannot completely cover the coverage area of the UE based on the location information of the neighboring SYN source, the UE will operate in the state because the SYN source decision program has succeeded. B 452. Moreover, if the jump point count difference between adjacent SYN sources is greater than 2 during a certain time period, the UE will operate in state B 452 because the decision has been successful.

When the UE is in a situation similar to that of FIG. 5 (where there is a first cluster 501 with a higher priority than the second cluster 502), if the pair is in a D2D resource pool (eg The error rate of the CRC check received by the data packet in 602) is greater than the threshold value, then the UE will blindly scan the SS containing the D2DSS and the PSS/SSS from the other cluster in a short period of time. If it has been determined that the D2DSS from another cluster is in a lower priority order, then since program A has succeeded, the UE will operate in state B 452 and will continue to synchronize to the D2DSS of the current cluster. However, if it has been determined that the SS from another cluster has a higher priority than the SS of the current cluster, then the UE will synchronize to the D2DSS with a higher priority, and thus this program is also considered successful and operates in state B 452 .

Further, the SYN source decision program B of the fourth exemplary embodiment is described as follows. If the UE cannot extend the coverage so that the coverage area of the adjacent SYN source can completely cover the coverage area of the UE based on the location information of the adjacent SYN source, or if the SYN source is based on the superior node information of the adjacent SYN source, it is not any phase The upper node of the neighboring SYN source, then the UE will operate in state A 451 because the program has failed. The superior node is the adjacent SYN source with the smallest hop count value.

For the fourth exemplary embodiment, the operation of the UE in the UNSYN state 454 will be the same as the first exemplary embodiment.

For operation of the UE as a normal UE rather than a SYN source in state A 451, the UE in state A 451 will periodically blindly scan SS, such as D2DSS and PSS/SSS. If PSS/SSS has been found, this would mean that the UE has detected an SS with a higher priority. The UE will then synchronize to PSS/SSS in step S401 and remain in the same state A 451. The UE will also monitor the D2D resource pool (e.g., 602) for D2D discovery and communication. The UE will also periodically monitor any D2DSS. Such as If multiple D2DSS have been found, the UE will perform step S401 by synchronizing to the highest priority order D2DSS and remaining in the same state. If the UE has lost the SS or D2DSS or missed the SS or D2DSS multiple times, the UE will perform step S405 and operate in the UNSYN state. The UE operating in state A 451 will also receive location information and hop count information for the neighboring SYN source of the UE. Subsequently, the UE can execute the SYN source decision program A of the aforementioned fourth exemplary embodiment.

The operation of the SYN source in state B 452 will be described as follows. The SYN source in state B 451 will periodically and blindly scan the SS containing D2DSS and PSS/SSS from other clusters. If a higher priority SS is found, then the SYN source will perform step S403 by synchronizing to the SS, updating the hop count and the superior node and remaining in state B452. The UE in state B 452 will periodically monitor the D2D resource pool (eg, 602) for D2D discovery and communication and will also monitor the D2DSS. The UE will update the hop count and the superior node when the initial superior node disappears. If the SS or D2DSS has been lost or missed multiple times, the UE will perform step S405 and operate in state UNSYN 454. The UE in state B 452 can also receive the hop count, location, and superior node information for its neighboring SYN source, periodically broadcasting its hop count and location and superior node information. The UE will periodically broadcast a D2DSS with a timing reference based on the received SS. Subsequently, the UE can execute the aforementioned SYN source decision program B.

The operation of the cluster header in state C 452 is described as follows. When operating as a standalone SYN source, the cluster head in state C 452 will periodically and blindly scan SSs containing D2DSS and PSS/SSS from other clusters. If found SS, then the cluster head will perform step S407 by synchronizing to the highest priority order SS, updating the jump point count and the superior node and operating in state B 452. The cluster head in state C 452 will also monitor the D2D resource pool (e.g., 602) for D2D discovery and communication. The cluster head in state C 452 will periodically broadcast its skip point count information and location information. The cluster header in state C 452 will also periodically broadcast the D2DSS with the timing reference from the highest priority SS. If the SS has not been discovered, the cluster head will periodically broadcast its own D2DSS without the aid of any external timing reference.

11 illustrates hardware elements of a UE in accordance with one of the exemplary embodiments of the present disclosure, in accordance with a functional block diagram. Exemplary UEs will include, but are not limited to, processing circuit 1101, analog to digital (A/D)/digital to analog (D/A) conversion circuit 1102, transmitter 1103 (TX), receiver (RX) 1104, one or more antennas 1105, and a non-transitory storage medium or memory unit (not shown) coupled to processing circuitry 1101. The UE will receive a radio frequency (RF) signal via one or more antennas 1105 that will be coupled to the receiver 1104 via a matching network and filter. Receiver 1104 will be coupled to A/D D/A converter 1102 and down-convert the RF signal directly or indirectly to baseband data. The baseband data is converted by the A/D converter 1102 into digital data to be transmitted to the processing circuit 1101. The UE will also transmit data by transmitting digital data to the D/A converter 1102 for conversion to baseband data. The baseband data is upconverted to RF data by a transmitter 1103 that transmits RF data via one or more antennas 1105.

Processing circuit 1101 will include one or more processing components such as a microprocessor, a microcontroller, and an application specific integrated circuit (ASIC). The D2D communication module 506 is included in the processing circuit 1101, and the D2D communication module will perform functions related to D2D communication, including directly or indirectly assisting in performing the proposed method (including the first, second, third, and Four exemplary embodiments). The storage medium can store programming code, buffered, and persistent data related to the operation of the proposed connection modification method.

In the present disclosure, the term "user equipment" (UE) may refer to various embodiments, which may include, for example, but are not limited to, a mobile station, an advanced mobile station (AMS), a server, a client, a desk. Laptop, laptop, network computer, workstation, personal digital assistant (PDA), personal computer (PC), scanner, telephone device, pager, camera, TV, handheld Video game devices, music devices, wireless sensors, and the like. In some applications, the UE may be a stationary computer device that operates in a mobile environment such as a bus, train, airplane, boat, car, or the like.

Figure 12 is a flow chart relating to a first exemplary embodiment of the present disclosure. In general, the first exemplary embodiment from the perspective of the UE may be summarized as follows. In step S1201, the UE will detect one or more synchronization signals transmitted from one or more neighboring synchronization sources. In step S1202, the UE will select a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is transmitted by a neighboring synchronization source having a hop count count = i, where The jump point count is the number of hops from the eNB to the neighboring synchronization source, and i is detected from the one or more neighboring synchronization sources. Minimum jump point count. In step S1203, the UE will determine whether there is more than one adjacent synchronization source with a hop count count = i, and if so, in step S1204, the UE will select the first SS from one or more adjacent synchronization sources as having The maximum reference signal received power (RSRP) detected by the UE. In step S1205, the UE will determine whether the RSRP of the first SS does not exceed a predefined threshold. If so, then in step S1206, the UE will operate as a synchronization source, and in step S1207, the UE will transmit the SS based on the first SS.

Optionally, if the RSRP of the first SS exceeds a predefined threshold, the UE will not operate as a synchronization source but will synchronize to the first SS.

The UE may optionally perform a cyclic redundancy code (CRC) check on data packets received from one or more neighboring UEs. The UE may scan for a second SS transmitted from an adjacent synchronization source belonging to another N-hop synchronization network in response to the error rate of the CRC check exceeding the error rate threshold. If it is determined that the priority order of the second SS is higher than the first SS, the UE will operate as a synchronization source and transmit the SS based on the second SS. If it is detected that the priority of the second SS is lower than the first SS, the UE will operate as a synchronization source and transmit the SS based on the first SS.

In response to the UE operating as a synchronization source, the UE may optionally also periodically scan the second SS from neighboring synchronization sources belonging to another N-hop synchronization network, and the priority order of the second SS is higher than In the case of an SS, the SS is transmitted based on the second SS.

Optionally, operating as a synchronization source may further comprise periodically scanning the primary SS (PSS) and the secondary SS (SSS), periodically scanning the same from the same a third SS of the adjacent synchronization source of the N-hop synchronization network, transmitting the SS based on the PSS and the SSS if the PSS and the SSS are detected; and otherwise, detecting the third SS and the third SS The SS is transmitted based on the third SS in the case where the priority order is higher than the first SS.

Furthermore, operating as a synchronization source may optionally include configuring the UE's hop count to be n if the UE transmits an SS based on another SS transmitted by a neighboring synchronization source having a lower hop count n-1 The jump point count is periodically broadcast.

In response to not operating as a synchronization source, the UE may optionally periodically scan the PSS and SSS, periodically scanning the third SS from neighboring synchronization sources belonging to the same N-hop synchronization network, detecting PSS and SSS In the case of synchronization to the PSS and SSS, but otherwise synchronized to the third SS if the third SS is detected and the priority of the third SS is higher than the first SS.

In response to losing the first SS, the UE may also optionally scan one or more synchronization signals during a fixed period. If the UE fails to detect one or more synchronization signals during the fixed period, the UE may operate as a cluster header and transmit the SS without timing reference.

If the UE is operating as a cluster header, the UE may optionally periodically scan for a second SS from a neighboring synchronization source belonging to another N-hop synchronization network. If the priority order of the second SS is higher than the UE, the UE may optionally operate as a synchronization source and transmit the SS based on the second SS.

Optionally, the UE may also periodically scan the PSS and SSS. If detected To the PSS and SSS, the UE can operate as a synchronization source and transmit the SS based on the PSS and SSS. Further, the UE may further configure the UE's hop count to zero and periodically broadcast the hop count.

Figure 13 is a flow chart relating to a second exemplary embodiment of the present disclosure. In step S1301, the UE will detect one or more synchronization signals transmitted from one or more neighboring synchronization sources. In step S1302, the UE will select a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is a neighboring synchronization source having a hop count = i or i+1 Transmitting, wherein the hop count counts the number of hops from the eNB to the neighboring synchronization source, and i is the minimum hop count count detected from the one or more neighboring synchronization sources. In step S1303, the UE will determine whether there is more than one adjacent synchronization source having a hop count count = i or i+1, and if so, the UE will select SS from one or more adjacent synchronization sources in step S1304. Has the maximum reference signal received power (RSRP) detected by the UE. In step S1305, the UE will determine whether the RSRP of the first SS does not exceed a predefined threshold. If so, then in step S1306, the UE will operate as a synchronization source, and in step S1307, the UE will transmit the second SS based on the first SS.

Figure 14 is a flow chart relating to a third exemplary embodiment of the present disclosure. In step S1401, the UE will detect one or more synchronization signals transmitted from one or more neighboring synchronization sources. In step S1402, the UE will select a first synchronization signal (SS) from the one or more synchronization signals, wherein the first SS is transmitted by a neighboring synchronization source having a hop count = i, wherein The hop count is the number of hops from the eNB to the neighboring synchronization source, and i is detected from the one or more neighboring synchronization sources The minimum jump point count. In step S1403, the UE will determine if there is more than one adjacent synchronization source with a skip point count = i. If so, then in step S1404, the UE will select the first SS to have the maximum reference signal received power (RSRP) detected by the UE. In step S1405, the UE will determine whether the skip point count difference of the adjacent synchronization source is greater than two. If so, then in step S1406, the UE will operate as a synchronization source, and in step S1407, the UE will transmit the second SS based on the first SS.

Figure 15 is a flow chart summarizing a fourth exemplary embodiment of the present disclosure. In step S1501, the UE will detect one or more synchronization signals transmitted from one or more neighboring synchronization sources. In step S1502, the UE will select a first synchronization signal (SS) from the one or more synchronization signals, wherein: the first SS is transmitted by a neighboring synchronization source having a hop count = i, where The jump point count is the number of hops from the eNB to the neighboring synchronization source, and i is the minimum hop count count detected from the one or more neighboring synchronization sources. In step S1503, the UE determines whether the UE can extend the coverage based on the location information of the neighboring synchronization source. If so, then in step S1504, the UE will operate as a synchronization source, and in step S1505, the UE will transmit the second SS based on the first SS.

In view of the foregoing description, the present disclosure is suitable for use in an N-hop synchronous wireless communication network and can provide synchronization to devices located outside of the coverage of the network to extend the D2D wireless coverage of the synchronous network, minimizing the SYN source. The number and the propagation delay within the coverage of the D2DSS is minimized.

The elements, acts or instructions in the detailed description of the disclosed embodiments of the disclosure should not be construed as being absolutely critical or essential to the present disclosure unless explicitly So described. Moreover, as used herein, the word "a" can encompass more than one item. If you want to represent only one item, you can use the term "single" or similar language. Moreover, as used herein, the term "any of" preceding a list of items and/or plurality of item categories is intended to encompass the item and/or item type individually or in combination with other items and/or Any of the other item categories "any of the combinations", "any combination of", "any of the plurality", and/or any combination of the plurality. Also, as used herein, the term "set" is intended to encompass any number of projects, including zero. Also, as used herein, the term "number" is intended to include any number, including zero.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

S1201~S1207‧‧‧Steps

Claims (23)

A method for forming an N-hop synchronization network for inter-device communication, suitable for a User Equipment (UE), the method comprising: detecting one or more transmissions from one or more neighboring synchronization sources a synchronization signal; selecting a first synchronization signal from the one or more synchronization signals, wherein: the first synchronization signal is transmitted by a neighboring synchronization source having a jump point count of i, wherein the jump point count is The number of hops from an evolved Node B (eNB) to the neighboring synchronization source, and i is the minimum hop count count detected from the one or more neighboring synchronization sources; and if present And selecting, by the hop point, one or more adjacent synchronization sources of i, then selecting the first synchronization signal to have a maximum reference signal received power detected by the user equipment; and if the first synchronization signal The reference signal received power does not exceed a predefined threshold, then: operates as a synchronization source; and transmits a synchronization signal based on the first synchronization signal. The method of claim 1, further comprising: if the reference signal received power of the first synchronization signal exceeds the predefined threshold, operating as the synchronization source; and synchronizing to the First sync signal. The method of claim 1, wherein the operating as the synchronization source further comprises: Periodically scanning a second synchronization signal from a neighboring synchronization source belonging to another N-hop synchronization network; and based on the case where the priority of the second synchronization signal is higher than the first synchronization signal The second synchronization signal transmits a synchronization signal. The method of claim 1, wherein the operating as the synchronization source further comprises: periodically scanning a primary synchronization signal and an auxiliary synchronization signal; periodically scanning the synchronization from the same N-hop point a third synchronization signal of the adjacent synchronization source of the network; transmitting the synchronization signal based on the primary synchronization signal and the auxiliary synchronization signal in the case where the primary synchronization signal and the auxiliary synchronization signal are detected; and In the case where the third synchronization signal is detected and its priority is higher than the first synchronization signal, a synchronization signal is transmitted based on the third synchronization signal. The method of claim 1, wherein the operating as the synchronization source further comprises: at the user equipment based on transmitting by an adjacent synchronization source having a lower hop count n-1 The jump point count of the user equipment is configured to be n when a synchronization signal transmits a synchronization signal; and the jump point count is periodically broadcasted. The method of claim 2, wherein the operating as the synchronization source further comprises: Periodically scanning a primary synchronization signal and an auxiliary synchronization signal; periodically scanning a third synchronization signal from a neighboring synchronization source belonging to the same N-hop synchronization network; detecting the primary synchronization signal and the Sync to the primary synchronization signal and the secondary synchronization signal in the case of an auxiliary synchronization signal; and otherwise to the case where the third synchronization signal is detected and its priority is higher than the first synchronization signal, synchronization is performed The third synchronization signal is described. The method of claim 1, further comprising: responding to the loss of the first synchronization signal: scanning the one or more synchronization signals in a fixed period; and if the user equipment fails to The one or more synchronization signals are detected during the fixed period, then: operating as a cluster head; and transmitting the synchronization signal without timing reference. The method of claim 7, wherein the operating as the cluster head further comprises: periodically scanning a second synchronization signal from a neighboring synchronization source belonging to another N-hop synchronization network. And if the priority of the second synchronization signal is higher than the user equipment, operating as the synchronization source; and transmitting a synchronization signal based on the second synchronization signal. The method of claim 7, wherein the operating as the cluster head further comprises: periodically scanning a primary synchronization signal and an auxiliary synchronization signal; and if the primary synchronization signal and the location are detected The auxiliary synchronization signal is then operated as the synchronization source; and the synchronization signal is transmitted based on the primary synchronization signal and the auxiliary synchronization signal. The method of claim 7, wherein the operating as the cluster head further comprises: configuring the jump point count of the user equipment to be zero; and periodically broadcasting the jump point count. A method of forming an N-hop synchronization network for inter-device communication, characterized in that it is adapted to a user equipment, the method comprising: detecting one or more synchronizations transmitted from one or more neighboring synchronization sources a signal; selecting a first synchronization signal from the one or more synchronization signals, wherein: the first synchronization signal is transmitted by a neighboring synchronization source having a hop count of i or i+1, wherein the hopping The point count is the number of hops from the eNB to the neighboring synchronization source, and i is the minimum hop count count detected from the one or more neighboring synchronization sources; and if there is the hop count count as i Or one or more adjacent synchronization sources of i+1, then selecting the first synchronization signal to have a maximum reference signal received power detected by the user equipment; And if the reference signal received power of the first synchronization signal does not exceed a predefined threshold value, operating as a synchronization source; and transmitting a synchronization signal based on the first synchronization signal. The method of claim 11, further comprising: if the reference signal received power of the first synchronization signal transmitted by the adjacent synchronization source having a jump point count of i or i+1 Exceeding the predefined threshold value, then not operating as the synchronization source; and synchronizing to the first synchronization signal. The method of claim 11, wherein the operating as the synchronization source further comprises: periodically scanning a second synchronization signal from a neighboring synchronization source belonging to another N-hop synchronization network. And transmitting a synchronization signal based on the second synchronization signal if the priority of the second synchronization signal is higher than the first synchronization signal. The method of claim 11, wherein the operating as the synchronization source further comprises: periodically scanning a primary synchronization signal and an auxiliary synchronization signal; periodically scanning the synchronization from the same N-hop point a third synchronization signal of the adjacent synchronization source of the network; transmitting the synchronization signal based on the primary synchronization signal and the auxiliary synchronization signal if the primary synchronization signal and the auxiliary synchronization signal are detected; and Then, in the case where the third synchronization signal is detected and its priority is higher than the first synchronization signal, the synchronization signal is transmitted based on the third synchronization signal. The method of claim 11, wherein the operating as the synchronization source further comprises: at the user equipment based on being transmitted by an adjacent synchronization source having a lower hop count n-1 The jump point count of the user equipment is configured to be n when a synchronization signal transmits a synchronization signal; and the jump point count is periodically broadcasted. The method of claim 12, wherein the operating as the synchronization source further comprises: periodically scanning a primary synchronization signal and an auxiliary synchronization signal; periodically scanning the synchronization from the same N-hop point a third synchronization signal of the adjacent synchronization source of the network; synchronizing to the primary synchronization signal and the auxiliary synchronization signal if the primary synchronization signal and the secondary synchronization signal are detected; and otherwise detecting The third synchronization signal is synchronized to the third synchronization signal if its priority is higher than the first synchronization signal. The method of claim 11, further comprising: responding to the loss of the first synchronization signal: scanning the one or more synchronization signals in a fixed period; and if the user equipment fails to Detected during the fixed period The one or more synchronization signals, then: operate as a cluster head; and transmit the synchronization signal without a timing reference. The method of claim 17, wherein the operating as the cluster head further comprises periodically scanning the second synchronization from a neighboring synchronization source belonging to another N-hop synchronization network. a signal; and if the priority of the second synchronization signal is higher than the user equipment, operating as the synchronization source; and transmitting a synchronization signal based on the second synchronization signal. The method of claim 18, wherein the operating as the cluster head further comprises: periodically scanning a primary synchronization signal and an auxiliary synchronization signal; and if the primary synchronization signal and the location are detected The auxiliary synchronization signal is then operated as the synchronization source; and the synchronization signal is transmitted based on the primary synchronization signal and the auxiliary synchronization signal. The method of claim 18, wherein the operating as the cluster head further comprises: configuring the jump point count of the user equipment to be zero; and periodically broadcasting the jump point count. A method of forming an N-hop synchronization network for inter-device communication, adapted to a user equipment, the method comprising: detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; Selecting a first synchronization signal from the one or more synchronization signals, wherein: the first synchronization signal is transmitted by a neighboring synchronization source having a hop count of i, wherein the hop count is counted from the eNB to the phase The number of hops of the neighbor sync source, and i is the minimum hop count count detected from the one or more neighbor sync sources; and if there are more than one contiguous sync source with a jump point count of i, then The first synchronization signal is selected to have a maximum reference signal received power detected by the user equipment; and if the reference signal received power of the first synchronization signal does not exceed a predefined threshold or if the phase The difference of the jump point counts of the neighboring synchronization sources is greater than two, then: operating as a synchronization source; and transmitting a second synchronization signal based on the first synchronization signal. A method of forming an N-hop synchronization network for inter-device communication, adapted to a user equipment, the method comprising: detecting one or more synchronization signals transmitted from one or more neighboring synchronization sources; Selecting a first synchronization signal from the one or more synchronization signals, wherein: the first synchronization signal is transmitted by a neighboring synchronization source having a hop count of i, wherein the hop count is counted from the eNB to the phase Neighbor synchronization source jump The number of points, and i is the minimum hop count count detected from the one or more neighboring synchronization sources; and if the user equipment can extend coverage based on location information of neighboring synchronization sources or if the phase The difference of the jump point counts of the neighboring synchronization sources is greater than two, then: operating as a synchronization source; and transmitting a second synchronization signal based on the first synchronization signal. A method of forming an N-hop synchronization network for inter-device communication, adapted to a user equipment, the method comprising: synchronizing to a first synchronization signal; for receiving data from one or more neighboring user devices The packet performs a cyclic redundancy check; and scans a second synchronization signal transmitted from an adjacent synchronization source belonging to another N-hop synchronization network in response to the error rate of the cyclic redundancy check exceeding an error rate threshold And if the priority of the second synchronization signal is higher than the first synchronization signal, operating as the synchronization source; and transmitting a synchronization signal based on the second synchronization signal; and if the second synchronization The priority of the signal is lower than the first synchronization signal, then: operating as the synchronization source; and transmitting a synchronization signal based on the first synchronization signal.